South Korean President Moon Jae-in and his Chinese counterpart Xi Jinping agreed Thursday to further improve their countries' bilateral relations, while jointly calling for efforts by all concerned parties to help denuclearize North Korea, Seoul's presidential office said.

Xi called the new South Korean leader to congratulate him on his election this week, Moon's press secretary Yoon Young-chan said at a press briefing.

"The two heads of state discussed ways to improve South Korea-China relations, and exchanged their views on a wide ranges of issues related to the Korean Peninsula," the chief press official said.

Their conversation lasted around 40 minutes, Yoon said, adding that it marked the first time for a Chinese leader to call his or her South Korean counterpart to congratulate the latter on his or her election.

Moon came into office Wednesday, only one day after he won the rare presidential by-election caused by the March 10 ouster of his conservative predecessor, Park Geun-hye, due to corruption allegations.

South Korean President Moon Jae-in holds a telephone conversation with his Chinese counterpart Xi Jinping at his presidential office Cheong Wa Dae on May 11, 2017, as the Chinese leader called Moon to congratulate the latter on his recent election. (Photo courtesy of Cheong Wa Dae)

Relations between Seoul and Beijing have been growing sour amid the ongoing deployment of a U.S. missile defense system in South Korea.

The South Korean and Chinese leaders agreed to discuss ways to resolve the issue, first through their special envoys, Yoon said.

When the special envoys will be sent to each other has yet to be decided, but Xi has also invited Moon on a visit to his country, he noted.

"President Moon said he hoped to meet President Xi in the near future, and President Xi invited President Moon to Beijing on an official visit," Yoon told the press briefing.

Throughout his campaign, the new South Korean president had insisted that the new Seoul government must be given a chance to review and possibly reconsider the agreement reached by the former administration on the deployment of the U.S. missile defense system, the Terminal High Altitude Area Defense (THAAD).

Xi explained the reasons for Beijing's strong and repeated opposition against the THAAD deployment, according to Yoon.

Moon said he understood Beijing's position, but that many South Korean people and businesses in China were suffering due to China's apparent economic retaliation prompted by the deployment.

"He then asked President Xi to personally look into ways to resolve the issue of economic restrictions and sanctions against such entities," Yoon said.

Turning to regional issues, Moon and Xi agreed to work together in denuclearizing the communist North.

The image shows South Korean President Moon Jae-in (R) and his Chinese counterpart Xi Jinping. (Yonhap)

"They noted that it was important to ease tensions, and that all related countries must work together to this end. They also agreed that denuclearization of the Korean Peninsula was a joint objective of the two countries," Yoon said.(Yonhap)